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6/17/2007 - The Rocker Box and Ground Board - Build and finish

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After completing the rocker box on this telescope and comparing it to that of my 13.1 inch scope of the same design the shear size (and weight!) of this thing became apparent! With the finish work on the Rocker Box and Ground Board complete, final assembly of the telescope and final trim of the truss poles to the right length (visual test on the sky) will commence on the 23rd/24th....HOORAY!

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The rocker sides and ground board are made of 2 sheets of 3/4 inch cross-laminated HCHV plywood. Why so thick?...simple, short, rigid rocker box sides that transfer the 110+ lb. weight of the OTA directly to the ground will provide for virtually no shake in the eyepiece at ANY power. Here the rocker sides have had the arcs cut for the altitude bearings. The radius of these arc is 1/8 larger then the bearing to allow for the 1/8 thick teflon pads. The pads must be mounted 65-70 degrees apart. Any closer and the telescope will move too easily and could "jump" from the bearing. Any further and the telescope would "stick". Test fit of the mirror box between the rocker sides to determine the rocker box height by checking swing clearance. We need to fit an azimuth encoder under there. A Tale of Two Rocker Boxes.....yikes!!! (that's the 13.1 inch rocker box INSIDE the 20 inch rocker box). Again, look at how heavy and thick those sides are. Filling screw holes and applying poly-urethane.

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